This invention relates to laminates containing bituminous waterproofing layers adapted for waterproofing and sealing structures. More particularly, this invention relates to improve pre-formed flexible sheet like laminates of the pressure-sensitive or "self-adhesive" type for use in roofing applications as waterproofing membranes, which laminates employ layers of bituminous waterproofing compositions combined with metallic and polymeric film layers.
Flexible sheet-like laminates of support films and self-adhesive bituminous waterproofing layers pre-formed in the factory have been successfully employed in roofing applications as substitutes for the more conventional waterproofing membranes which are constructed at the job site by plying together one or more layers of bitumen-saturated paper or felt and bituminous adhesives. The pre-formed, self-adhesive laminate-membranes offer many advantages including factory controlled preparation, avoidance of heating equipment and handling of hot materials at the job site, as well as many performance advantages.
Flexible pre-formed laminates of the aforementioned type and their use to form waterproofing layers in various kinds of building structures are described for example in U.S. Pat. Nos. 3,741,856; 3,583,682 and 3,900,102 to John Hurst. Such patents describe in particular the preparation of flexible laminates containing a support material, for example a layer of a polymeric or metallic film, and a layer of self-adhesive, or pressure-sensitive adhesive, bitumen-elastomer waterproofing composition. As discussed in particular in U.S. Pat. No. 3,900,102, such laminates may ideally be constructed in the plant in the form of a roll with a protective sheet, for example siliconized paper applied against the self-adhesive bituminous waterproofing layer, transported to the job site, and thereafter applied to a substrate adhesive side down, each successive laminate strip being made to overlap the edge of the previously-applied strip of laminate to insure a continuous waterproofing seal.
In Canadian Pat. No. 1,008,738 to Everett R. Davis, improved waterproofing laminates of the type described in the aforementioned U.S. patents are described which utilize as the support material for such laminates, cross-laminated or biaxially oriented polymeric films. As discussed in the Canadian patent, such support films were found to provide laminates which exhibit reduced wrinkling following adhesion to a substrate and subsequent exposure to heat, for example, exposure to the sun. In recent years, flexible preformed laminates utilizing cross-laminated high density polyethylene films as the support layers for self-adhesive waterproofing layers of asphalt-rubber composition have been successfully applied in the form of overlapping strips to the rooftops of a variety of types of buildings to form long-lasting protective membranes against the passage of water and moisture. Protective coatings containing for example inert aggregates, pigments, metal flakes, etc., have been applied to the exposed surfaces of the overlapped laminates which significantly increase the life of the waterproofing laminate-membrane. However, there is a continuing need in the art for improved flexible laminates for use as waterproofing membranes for roofs of buildings and the like.